Exploration of potassium silicide compounds under high pressure.

Herein, we have performed extensive swarm-intelligence structures searching simulations on the KSi x (x = 4, 5, 6, 7, 8) compounds within the pressure range from 0 to 50 GPa. Seven crystal structures of potassium silicides are proposed, and the dynamic stability of these phases were explored in the corresponding pressure range. KSi 4 was predicted to be stable, and it was found to have two phases, named C 2 /m-a and C 2 /m - b , respectively. As for KSi 5 , two thermodynamically stable phases were determined as C 2 /m and Imma , respectively. Above 1.33 GPa, the proposed monoclinic phase with C 2 /m is energetically favorable. With the increasing pressure, our proposed new Imma phase becomes energetically favorable at 16 GPa. For KSi 6 , it was determined that has the following space groups, Cmcm , C 2 /m and P 6/ m. These findings provide insights for helping advance our understanding of the KSi x compounds under high pressure. • This work systematically explored the high-pressure open-framework crystal structures of KSi x (x = 4 ∼ 8) compounds. • Seven crystal structures of potassium silicides were proposed. • The thermal stability, dynamical stability and electronic of K-Si system were performed. [ABSTRACT FROM AUTHOR]